| 摘要 |
PURPOSE:To obtain a sintered silicon nitride compact excellent in mechanical strength and toughness by combining respective steps of coarse and dense calcining of a mixture compact of silicon nitride powder and sintering assistant powder with permeation of a Zr compound solution, calcining and sintering thereof. CONSTITUTION:A compact consisting of a mixture of silicon nitride powder with a sintering assistant powder is subjected to the following steps to produce the objective sintered silicon nitride compact. The first calcining step for calcining the above-mentioned compact until the bulk density attains 80-90% of the theoretical density to provide a calcined coarse and dense compact, a permeation step for permeating a solution of a zirconium compound dissolved therein for forming zirconium oxide by heating into open pores of the above-mentioned calcined coarse and dense compact, a calcining step for heating the calcined coarse and dense compact in which the solution is permeated and converting the zirconium compound into the zirconium oxide and the second sintering step for sintering the calcined coarse and dense compact containing the zirconium oxide to afford the afore-mentioned sintered silicon nitride compact. |
